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101.
《Surface and interface analysis : SIA》2003,35(6):544-547
We have developed multiple short‐period delta layers as a reference material for SIMS ultra‐shallow depth profiling. Boron nitride delta layers and silicon spacer layers were sputter‐deposited alternately, with a silicon spacer thickness of 1–5 nm. These delta‐doped layers were used to measure the sputtering rate change in the initial stage of oxygen ion bombardment. A significant variation of sputtering rate was observed in the initial 3 nm or less. The sputtering rate in the initial 3 nm was estimated to be about four times larger than the steady‐state value for 1000 eV oxygen ions. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
102.
采用表面改性法制备了负载型光催化材料CeO2-TiO2/SiO2,并用X射线衍射,比表面积测定,红外光谱,程序升温还原和紫外可见漫反射光谱技术对固体材料的结构和光响应性能进行了表征.结果表明,CeO2与TiO2在材料表面存在相互修饰作用,CeO2能拓展TiO2的光响应范围,使TiO2吸光区域由紫外拓宽至可见光区,从而提高材料的光能利用率;Ti4 可以进入CeO2晶格,形成Ce-O-Ti键合,使得Ti4 平均配位数增加,同时提高了CeO2体相晶格氧的活性;TiO2有助于提高CeO2在载体表面的分散程度,减小CeO2的微晶尺寸,提高固体材料的能隙值和氧化还原能力. 相似文献
103.
Akihiko Kanazawa Tomiki Ikeda Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1993,31(2):335-343
Various polymeric phosphonium salts and the corresponding low-molecular-weight model compounds were prepared and their antibacterial activities against Staphylococcus aureus and Escherichia coli were explored by the viable cell counting method in sterile distilled water. Antibacterial activity of the polymers was found to be higher than that of the corresponding model compounds, particularly against S. aureus. Furthermore, the polymeric phosphonium salt exhibited a higher activity by 2 orders of magnitude than the polymeric quaternary ammonium salt with the same structure except the cationic part. Compounds with the longest alkyl chain (octyl) studied were found to exhibit particularly high activity, and this finding may be ascribed to the contribution of the increased hydrophobicity of the compounds to the cidal activity. © 1993 John Wiley & Sons, Inc. 相似文献
104.
According to the new method of preparing core-shell nanospheres developed by our group, by using two monomers, 2-hydroxypropyl
methacrylate(HPMA) and vinyl acetate(VAc), two kinds of core-shell nanospheres with poly(ɛ-caprolactone) (PCL) as the core
and crosslinked poly(2-hydroxypropyl methacrylate) (PHPMA) or poly(vinyl acetate) (PVAc) as the shell were successfully prepared
under similar conditions. After degrading the PCL cores of the two kinds of nanospheres by lipase, the corresponding crosslinked
poly(methyl acrylic acid) hollow spheres and crosslinked poly(vinyl alcohol) hollow spheres were obtained. Results indicate
that the new method we proposed for preparing core-shell polymeric nanospheres via in-situ polymerization can be generalized to a certain extent, and it is suitable for many systems provided the monomer used is soluble
in water, while its corresponding polymer is insoluble in water.
Translated from Chemical Journal of Chinese University, 2006, 27(9): 1762–1766 [译自: 高等学校化学学报] 相似文献
105.
采用溶胶-凝胶法合成了一种V2O5/C复合材料.扫描电镜(SEM)和红外光谱(FTIR)分析表明,这是一种外层V2O5胶体包覆内层乙炔分子的多孔复合材料.以V2O5/C作正极,锌片为负极,Zn(ClO4)2溶液为电解质组成水相锌二次电池,采用循环伏安(CV)和电化学阻抗谱(EIS)等方法研究发现:V2O5:C质量比为1:1时电极具有最好的电化学性能,电池开路电压达1.64 V; Zn2+能分别在1.01 V和1.26 V处分步嵌入V2O5/C结构中A、B两种位置,其嵌入电流密度峰值最高可达70 mA•g-1,并且具有较好的循环充放电性能;在一定放电深度下,V2O5/C电极反应速率受Zn2+的扩散过程控制. 相似文献
106.
锂离子电池正极材料LiMn2O4的合成与晶体结构(英) 总被引:2,自引:0,他引:2
Spinel LiMn2O4 powders were prepared using two-step synthesis method consisting of solid-state reaction method and citrate modified sol-gel method. The effects of the calcination temperature and the Li/Mn ratio of raw materials were studied on the physicochemical and electrochemical properties of the spinel LiMn2O4 powders, such as crystallinity, lattice constant and density. The title compound was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Polycrystalline LiMn2O4 powers calcined at 750 ℃ were found to be composed of very uniformly-sized microcrystal with an average particle size of 300 nm. The improvement in electrochemical properties was mainly attributed to the process of re-grinding by absolute alcohol. 相似文献
107.
Polyethylene based composites are attractive materials for advanced circuit board applications because of their unique combination of properties: low dielectric constant and loss factor, light weight, high flexural modulus and low thermal expansion coefficient controlled in all spatial directions. This investigation describes a process to consolidate chopped fibers of ultra‐high molecular weight polyethylene concurrently with its bonding to a copper foil. Bonding is affected by a thin sheet of low‐density polyethylene, incorporating a crosslinking agent with a concentration gradient across the sheets thickness. In this single step process, the composite material is formed and bonded to the metal foil, achieving good adhesion without the use of extraneous glue. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
108.
孔壁部分有序化的介孔二氧化硅材料的合成与表征 总被引:4,自引:0,他引:4
采用一种“改进的二次晶化”的方法处理介孔二氧化硅SBA-15. 用X射线衍射(XRD)、 透射电镜(TEM)、 电子衍射(ED)、 红外光谱(FTIR)以及固体核磁共振(NMR)等多种技术对样品进行了表征. 结果表明, 在所得样品的孔壁中, 原子的排列方式与普通介孔二氧化硅材料的孔壁不同, 显示一定程度的有序性. 同时, 高度有序的介孔结构得到很好的保持, 且样品的水热稳定性大幅度提高. 相似文献
109.
110.
Various diblocks, triblocks and a graft copolymer of butadiene with 4-vinylpyridine short blocks have been prepared. They were complexed with ZnCl2 to give ionomer-like materials. For all copolymers, the Tg of the elastomeric block (?84°C to ?91°C) was unchanged by complexation. For all diblocks and triblocks with short blocks (DP n ~ 3) the storage modulus was only slightly increased by comparison with uncomplexed materials. For the graft copolymer even with short blocks the material is less sensitive to temperature after complexation. For triblocks, when the DP n of the vinylpyridine blocks was high enough (15 units), complexes were associated in multiplets of large size and the elastomeric properties were retained up to 200°C. 相似文献